We will continue on molluscan neurons to investigate the role of Ca entry in cell metabolism and membrane function. These problems will be approached with voltage clamp, local membrane-current recording (patch method) and Ca-sensitive photometric techniques. Specific ion-blocking agents and intracellular ion replacement techniques will be used to investigate facilitation of membrane conductance, Ca-regulated K conductance, and other phenomena relevant to membrane function at pre-and postsynaptic membranes.